The advice already given is good. We went through this with my Mom and MIL, but both had hospitalizations before they moved in with us, and the Drs told us they could no longer live alone in front of them. My mothers response was, as expected, "What do YOU know?" My MIL had a stroke that robbed her of much of her memories about where she lived, etc. and came to us willingly - sort of. With my mother, my siblings had been aware that she needed 24 hour supervision for awhile, but were reluctant to act on it. I live in another state and happened to be visiting when she was hospitalized. I am the 'It has to be done, so let's do it now' type, so after discussing the situation with my siblings, just told her she wasn't going back to her home because the DR said she couldn't live alone anymore. Of course, she objected - called me "The Warden" and told me it would be like being in prison, but I would not be bullied. To get herself out of the hospital, she came with us, then tried to make herself enough of a pain in the neck that we would throw her out. That didn't work and after a while she settled in as much as she could settle in.
The point is that it is difficult for both you and for your parent when the roles of caretaker and child are reversed. Many of us have been through it and understand what you are going through, so don't hesitate to confide in us.
I will say a prayer for you and your father.